1. Field of the Invention
The present invention relates to hair irons for straight permanents, which hair irons are used in barber shops or beauty parlors to make curly hair straight.
2. Background Information
A conventional example of a hair iron for straight permanents is that described in the Japanese official gazette for Provisional Publication No. 189818/H6. That hair iron for straight permanents has a pair of arms joined by a pivot to enable opening and closing, with hair pinching parts being formed in such a way that they approach and leave in accordance with the opening and closing of the arms. An array of convex and concave patterns in a waveform cross section is formed in the extension of the arms so as to engage the complementary pattern in the opposing arm.
Thus, with that conventional hair iron, it is possible to make curly hair straight by holding the pair of arms, opening and closing them so as to pinch the hair, and then sliding them from the hair root to the hair tip, or moving them little by little from the hair root toward the hair tip while pressing the hair with the gripping pressure of the arms.
However, that conventional hair iron for straight permanents, with an array of convex and concave patterns having a waveform cross section in the hair pinching part, employs waveforms having a uniform pitch.
There are various types of hair, such as thick and coarse, and on the other hand, thin and soft. So, when creating a straight permanent, it is necessary to use a strong corrective force on thick and coarse hair, while it is important to use a light corrective force on thin and soft hair to prevent damage. Thus, it is necessary to apply a corrective force in accordance with the nature of the hair, taking into consideration the balance between the corrective force and probable hair damage. Whereas, with previous designs, waveforms were made with the same pitch, requiring the same corrective force. As a result, in order to apply a corrective force in accordance with the nature of a particular type of hair, it has been necessary to prepare several hair irons for straight permanents with different waveform pitches.
Also, when only one type of hair iron is used for straight permanents, it is necessary to use fine techniques such as adjusting the movement of the hair iron in accordance with the nature of the hair, or adjusting the gripping pressure of the hair pinching parts. This leads to a problem in that a satisfactory permanent can be carried out only by skilled hairdressers.
The present invention is aimed at overcoming the above-mentioned problems. Thus, an object of the present invention is to provide a hair iron for straight permanents which can be satisfactorily used not only by skilled hairdressers, but also by those with less experience. The invention also makes it possible to carry out a straight permanent by applying a corrective force in accordance with the nature of the hair, taking into consideration the balance between the corrective force and probable hair damage with the use of only one hair iron.